Exhaust system for internal combustion engines

Abstract

The present invention provides an exhaust system (6) for an internal combustion engine (4) having at least one exhaust pipe (7) originating from the internal combustion engine (4) and having an end portion (9) terminating at an outlet orifice (10) through which exhaust gases are released into the atmosphere. The end portion (9) of the exhaust pipe (7) has at least one movable wall (16) movable to different positions to change the width of the outlet orifice (10). The system includes: a motor-driven actuator (17) configured to move the movable wall (16) and capable of being electronically controlled; and a control unit (17) configured to change the position of the movable wall (16) by controlling the actuator (17) according to the rotational speed and engine load of the internal combustion engine (4).

Description

[0001] Cross-references to related applications

[0002] This patent application claims priority to Italian Patent Application No. 102020000007627, filed on April 9, 2020, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This invention relates to an exhaust system for an internal combustion engine. Background Technology

[0004] Car type approval rules require manufacturers to limit noise emission levels, especially when the car is traveling at moderate speeds (i.e., when passing through city centers). Therefore, the exhaust system (which functions to release combustion gases into the atmosphere and limit the amount of noise and pollutants) always includes at least one muffler, which is arranged downstream of the pollutant reduction device along the exhaust pipe.

[0005] Generally, a muffler comprises a tubular body, typically with an elliptical cross-section and an inlet and an outlet. A tortuous path is defined within the tubular body, determining the path of exhaust gas from the inlet to the outlet; this tortuous path typically includes diaphragms (or baffles) and tubes, the diaphragms being arranged laterally (i.e., perpendicular to the longitudinal axis of the tubular body) to define chambers within the tubular body, and the tubes connecting the chambers to each other. In conventional mufflers that ensure high noise attenuation at low engine speeds, the exhaust back pressure generated by the muffler (i.e., the pressure loss in the exhaust gas as it flows through the muffler) increases exponentially with increasing engine speed (i.e., with increasing average exhaust gas velocity). As a result, to avoid excessively high exhaust back pressure values ​​at high engine speeds (and thus, to avoid excessive performance degradation at high engine speeds), a bypass duct was provided that was arranged parallel to the muffler (i.e., designed to bypass the muffler) and regulated by a bypass valve that remained closed at low engine speeds (to maximize silencing effect at the expense of performance that is not necessary at low engine speeds) and remained open at high engine speeds (to reduce exhaust back pressure at the expense of silencing performance that is not of primary importance at high engine speeds).

[0006] Furthermore, in high-performance sports cars, the noise of the internal combustion engine perceived inside the cabin is crucial. In particular, a significant component of judging a high-performance sports car is the "quality" of the exhaust system's sound (not just, and not primarily, in terms of sound intensity, but especially in terms of the "possibility" of the sound produced). That is, the user satisfaction with a high-performance sports car is significantly influenced by the "quality" of the exhaust system's sound. However, known exhaust systems with variable geometry (i.e., equipped with one or more electrically or pneumatically controlled valves that can alter the path of exhaust gases and thus the path of the sound along the exhaust system) do not always ensure that the exhaust system's sound meets the user's expectations.

[0007] Generally speaking, turbocharged engines are disadvantageous because the presence of a turbine along the exhaust pipe and a compressor along the intake pipe increases the need for filters and reduces the noise levels of both the exhaust and intake systems.

[0008] Furthermore, the recent EURO6C emission standard has established the use of exhaust gas treatment devices, which severely compromise sound performance because even in gasoline engines, a particulate filter (also known as a GPF, or "gasoline particulate filter") must be present in series with the catalytic converter.

[0009] Patent documents US1483354A, KR20160108625A, and GB2274681A describe an exhaust system for an internal combustion engine, wherein an exhaust pipe originating from the internal combustion engine has an end portion terminating at an outlet orifice through which exhaust gases are released into the atmosphere; the end portion of the exhaust pipe has at least one movable wall that can be moved to different positions to change the width of the outlet orifice. In particular, the movement of the movable wall can be performed manually (as described in US1483354A) or automatically due to the pressure of the exhaust gases and overcoming an elastic thrust generated by a spring that tends to minimize the width of the outlet orifice (as described in KR20160108625A and GB2274681A). Summary of the Invention

[0010] The object of the present invention is to provide an exhaust system for an internal combustion engine; the exhaust system allows the manufacturer to obtain natural exhaust noise under all operating conditions, which is satisfactory to the driver and possible passengers, while complying with type approval regulations and without compromising performance.

[0011] According to the present invention, an exhaust system for an internal combustion engine is provided.

[0012] The exhaust system includes at least one first exhaust pipe originating from an internal combustion engine and having an end portion that terminates at a first outlet port through which exhaust gas is released into the atmosphere;

[0013] The end portion of the first exhaust pipe has at least one movable wall that can be moved to different positions to change the width of the outlet orifice; and

[0014] The exhaust system is characterized in that it includes:

[0015] A motor-driven actuator device configured to effectively move a movable wall and capable of being electronically controlled; and

[0016] The control unit is configured to change the position of the movable wall by controlling the actuator device according to the speed of the internal combustion engine and the engine load of the internal combustion engine.

[0017] The appended claims describe preferred embodiments of the invention and form part of the description. Attached Figure Description

[0018] The invention will now be described with reference to the accompanying drawings, which illustrate some non-limiting embodiments of the invention, wherein:

[0019] · Figure 1 This is a schematic diagram of a car driven by an internal combustion engine having an exhaust system according to the present invention;

[0020] · Figure 2 , Figure 3 and Figure 4 It is a corresponding variant with an exhaust system. Figure 1 A schematic diagram of a car;

[0021] · Figure 5 It has Figures 1 to 4 A schematic diagram of the end portions of the two movable walls of the exhaust pipe of the exhaust system;

[0022] · Figure 6 , Figure 7 and Figure 8 This applies when the movable wall is located in different positions. Figure 4 A schematic diagram of the end portion;

[0023] · Figure 9 yes Figure 5 A schematic perspective view of the end portion; and

[0024] · Figure 10 yes Figure 5 A schematic exploded three-dimensional view of the end portion. Detailed Implementation

[0025] exist Figure 1 In the accompanying drawing, reference numeral 1 generally indicates a car with two front wheels 2 and two rear drive wheels 3, the rear drive wheels 3 receiving torque from an internal combustion engine 4, which is turbocharged and positioned at the front. The car 1 has a passenger compartment 5, which is designed to accommodate the driver and possible passengers.

[0026] According to a feasible but non-limiting embodiment, the internal combustion engine 4 is a "V8" engine and has two (double) cylinder banks with four cylinders each, arranged at an angle relative to each other to form a "V". In each bank, the four cylinders are connected to an intake manifold (not shown) via two intake valves and to an exhaust manifold (not shown) via two exhaust valves; each exhaust manifold collects the combustion gases, which flow out periodically through the exhaust valves.

[0027] The internal combustion engine 4 is equipped with an exhaust system 6, which functions to release combustion-produced gases into the atmosphere and limit noise and pollutant levels. The exhaust system 6 includes two (dual) exhaust pipes 7, each originating from a corresponding exhaust manifold to receive combustion-produced gases from the exhaust manifold and terminating in the rear area of ​​the vehicle 1. Along each exhaust pipe 7, there are known exhaust treatment devices 8: there is always at least one catalytic converter, and possibly a particulate filter (to comply with the new EURO6C standards regarding pollution emissions, automakers also use particulate filters called GPF (an abbreviation for "Gasoline Particulate Filter") in gasoline engines).

[0028] Each exhaust pipe 7 (derived from the internal combustion engine 4) has an end portion 9 that terminates at an outlet port 10 through which exhaust gases are released into the atmosphere.

[0029] System 6 includes two additional exhaust ducts 11 (i.e., in addition to the two exhaust ducts 7), each of which originates from the region of the junction 12 of the corresponding exhaust duct 7 and has an outlet 13 through which exhaust gases are released into the atmosphere. In other words, each additional exhaust duct 11 is a replacement for the final section of the corresponding exhaust duct 7. Along each additional exhaust duct 11, there is (at least) a conventional muffler 14, for example, which includes a tubular body with an elliptical cross-section, an inlet or outlet, and an internal tortuous path that determines the path of the exhaust gases from the inlet to the outlet. On the other hand, each exhaust duct 7 is not provided with any conventional muffler.

[0030] System 6 includes two regulating valves 15, each arranged downstream of the joint 12 from which the exhaust duct 11 originates (i.e., between the joint 12 and the end portion 9 of the exhaust duct 11) along the corresponding exhaust duct 7, and designed to regulate the exhaust gas flow toward the end portion 9 of the exhaust duct 7. Specifically, the regulating valves 15 move toward a fully closed position to prevent exhaust gas from flowing into the final section of the exhaust duct 7, thus forcing the exhaust gas flow through the exhaust duct 11 equipped with a muffler 14, resulting in significant noise reduction and a large back pressure; conversely, the regulating valves 15 move toward a fully open position to direct the exhaust gas flow toward the final section of the exhaust duct 7 (without needing to close the exhaust duct 11, as the large back pressure generated by the muffler 14 minimizes the exhaust gas flow along the exhaust duct 11 when a freer alternative path is available).

[0031] exist Figure 2 In the variant shown, there is no regulating valve 15, and the function of the regulating valve 15 (i.e., regulating the exhaust flow toward the end portion 9 of the exhaust pipe 7) is directly achieved by the variable geometry of the end portion 9 of the exhaust pipe 7 (described below).

[0032] exist Figure 3 In the variant shown, there is no exhaust pipe 11 (and therefore no associated muffler 14), but on the other hand, there are regulating valves 15, each of which intersects with the exhaust pipe 7 and can move between a fully open position and a fully closed position.

[0033] In this embodiment, the regulating valve 15 has a dedicated function to reduce noise transmission to the outlet port 10. Therefore, in the fully closed position, the regulating valve 15 has a free section for allowing exhaust gas to pass through. The area of ​​the free section is non-zero, so that exhaust gas can flow through the regulating valve 15 even when the valve 15 is in the fully closed position.

[0034] exist Figure 4 In the variant shown, there is no exhaust pipe 11 (and therefore no associated muffler 14), nor is there a regulating valve 15; as a result, the entire management of the sound attenuation strategy is entirely assigned to the variable geometry of the end portion 9 of the exhaust pipe 7 (described below).

[0035] according to Figures 5 to 10 Each exhaust pipe 7 has two movable walls 16 at its end portion 9 that are opposite to and face each other, and these movable walls can be moved to different positions (compare). Figures 5 to 8(It is quite obvious). Each end portion 9 is provided with a motor-driven actuator device 17 (i.e., provided with a preferably electric or pneumatic motor designed to effectively generate movement), which is configured to move the movable wall 16; preferably, each actuator device 17 is configured to move the two movable walls 16 together in opposite directions, so that the two movable walls 16 move separately or move the movable walls 16 closer to each other. In other words, each motor-driven actuator device 17 is effective and electronically (electrically) controlled to generate a force (torque) that determines the movement of the movable wall 16; as a result, in each end portion 9, the position of the movable wall 16 is adjustable (by controlling the corresponding actuator device 17) and is completely independent of the pressure and velocity of the exhaust gas flowing through the end portion 9 (for example, when the pressure and velocity of the exhaust gas are moderate, the movable wall 16 can be moved to have a very large outlet orifice 10, while when the pressure and velocity of the exhaust gas are high, the movable wall 16 can be moved to have a very small outlet orifice 10).

[0036] According to a preferred embodiment, each movable wall 16 is hinged to rotate about a rotation axis 18; as a result, each actuator device 17 is configured to always cause the two movable walls 16 to rotate about their respective rotation axes 18 in opposite directions (in this way, the movement of the two movable walls 16 causes the two movable walls 16 to move apart from each other, or causes the two movable walls 16 to move closer to each other).

[0037] In the end portion 9 of each exhaust pipe 7, two movable walls 16 can be in the maximum expansion position (e.g., at...). Figure 5 (as shown in the diagram) and the minimum expansion location (e.g., in...) Figure 8 The movable walls 16 move between (as shown in the diagram); obviously, when the two movable walls 16 are in their maximum expanded positions (e.g., in...), Figure 5 As shown in the diagram, the area of ​​the outlet hole 10 is significantly larger than the area of ​​the outlet hole 10 when the two movable walls 16 are in their minimum expansion positions (e.g., in...). Figure 8 (as shown in the image).

[0038] At the location of maximum expansion (e.g., at) Figure 5 (as shown in the image) or even in other expansion locations (e.g., in...) Figure 6 (As shown in the diagram), the two movable walls 16 give the end portion 9 of the exhaust pipe 7 a diverging structure, which causes the cross-sectional area near the outlet orifice 10 to gradually increase; that is, at the maximum expansion position (in Figure 5 (as shown in the image) or even in other expansion locations (e.g., in...) Figure 6 As shown in the figure, the two movable walls 16 give the end portion 9 of the exhaust pipe 7 a horn shape.

[0039] According to a feasible implementation, at the minimum expansion position (in Figure 7 As shown in the figure, the two movable walls 16 give the end portion 9 of the exhaust pipe 7 a parallel configuration that keeps the area of ​​the cross-section near the outlet hole 10 constant (basically, the two movable walls 16 are arranged parallel to the wall of the front portion of the exhaust pipe 7 so as not to determine any significant change in the area of ​​the cross-section).

[0040] According to an alternative implementation, at the minimum expansion position (in Figure 8 As shown in the figure, the two movable walls 16 give the end portion 9 of the exhaust pipe 7 a converging structure that gradually reduces the area of ​​the cross section near the outlet hole 10.

[0041] Each actuator device 17 is capable of positioning and holding the two movable walls 16 in their maximum expanded position (e.g., in...). Figure 5 (as shown in the diagram) and the minimum expansion position (e.g., in Figure 8 (shown in the image) The middle position between them.

[0042] according to Figure 9 and Figure 10 In the possible implementation shown, in each end portion 9: two movable walls 16 face each other and are opposite to each other, and are hinged to rotate about two corresponding axes of rotation 18 that are parallel to each other; there are two fixed walls 19 that are parallel to each other and perpendicular to the axes of rotation 18 (i.e., rigidly connected to the support structure, and therefore cannot allow any kind of movement); and the two movable walls 16 are surrounded between the fixed walls 19 and travel slowly on the fixed walls 19 when the two movable walls 16 move. In each end portion 9, the two fixed walls 19 may also be connected to each other to form a "U"-shaped structure containing the two movable walls 16 inside, or to form a structure that is closed in an annular shape and contains the two movable walls 16 inside.

[0043] In the embodiment shown in the accompanying drawings, each exhaust pipe 7 end portion 9 has two movable walls 16 facing each other and opposing each other; according to different embodiments not shown herein, each exhaust pipe 7 end portion 9 has a single movable wall 16 or three or more movable walls 16.

[0044] As described above, each exhaust duct 7 has no conventional silencer (i.e., except for the movable wall 16 and located upstream of the movable wall 16).

[0045] It also includes a control unit 20 (in Figures 1 to 4(Illustrated schematically) The control unit 20 is configured to change the position of the movable wall 16 of each end portion 9 (by controlling the corresponding actuator device 17) according to the following conditions: the rotational speed of the internal combustion engine 4, the engine load of the internal combustion engine 4, the gear engaged in the gearbox connected to the internal combustion engine 4, the longitudinal speed of the vehicle 1 equipped with the internal combustion engine 4, and the longitudinal acceleration of the vehicle 1 equipped with the internal combustion engine 4.

[0046] That is, the control unit 20 is configured to detect (e.g., by reading them from the vehicle’s BUS network): the speed of the internal combustion engine 4, the engine load of the internal combustion engine 4, the gear engaged in the transmission, the longitudinal speed of the vehicle 1, and the longitudinal acceleration of the vehicle 1; knowing this information (read in advance), the control unit 20 can determine the position of the movable wall 16 of each end portion 9 based on this information.

[0047] The control unit 20 can be configured to also change the position of the movable wall 16 of each end portion 9 according to the driving mode selected by the driver (i.e., it can be sport driving mode, racing driving mode, city driving mode, highway driving mode, slippery road driving mode, etc., which is usually selected by the driver by acting on a selector called a "hand lever").

[0048] According to a preferred embodiment, the control unit 20 is configured to move the movable wall 16 of each end portion 9 towards its minimum expansion position at low speeds and low engine loads of the internal combustion engine 4, and to move the movable wall 16 of each end portion 9 towards its maximum expansion position at high speeds and high engine loads of the internal combustion engine 4. Furthermore, the control unit 20 is configured to move the movable wall 16 of each end portion 9 towards its minimum expansion position in low gears, and to move the movable wall 16 of each end portion 9 towards its maximum expansion position in high gears.

[0049] According to a preferred embodiment, different patterns (each pattern corresponding to one or more driving modes) are stored in the control unit 20. These patterns, based on data provided as input regarding the speed and load of the internal combustion engine 4 and the gear engaged in the transmission coupled to the internal combustion engine 4, provide the desired (ideal) position of the movable wall 16 of each end portion 9 as output. Clearly, each pattern stored in the control unit 20 includes a finite number of points; therefore, the control unit 20 can perform interpolation between the closest points of the patterns to determine the desired (ideal) position of the movable wall 16 of each end portion 9.

[0050] At the location of maximum expansion (e.g., at) Figure 5As shown in the diagram, the "open" (i.e., "divergent") position of the movable wall 16 of each end portion 9 minimizes the exhaust back pressure of the exhaust duct 7 (i.e., maximizes performance) and also minimizes the exhaust noise attenuation capability of the exhaust duct 7; on the other hand, in the minimum expansion position (e.g., at...), Figure 8 As shown in the figure, the “closed” (i.e. “converging”) position of the movable wall 16 of each end portion 9 gives the exhaust pipe 7 the maximum exhaust back pressure (i.e., which impairs performance to a large extent) and also gives the exhaust pipe 7 the maximum exhaust noise attenuation capability.

[0051] The control unit 20 is configured to move the movable wall 16 of each end portion 9 toward a position of minimum expansion (e.g., in) when it is necessary (useful) to prioritize noise reduction rather than performance. Figure 8 (as shown in the diagram) move, and when it is necessary (useful) to prioritize performance over noise reduction, move the movable wall 16 of each end portion 9 toward the position of maximum expansion (e.g., in...). Figure 5 (As shown in the image) Move.

[0052] In the embodiment shown in the accompanying drawings, the internal combustion engine 4 has eight cylinders 6 arranged in a V-shape. Clearly, internal combustion engines can have different numbers of cylinders and / or different cylinder arrangements; for internal combustion engines with inline cylinders (and therefore a separate row of cylinders), there is typically a single exhaust pipe 7, and thus an end portion 9.

[0053] In the embodiment shown in the accompanying drawings, the internal combustion engine 4 is turbocharged; according to other embodiments not shown herein, the internal combustion engine 4 is not turbocharged, i.e., it is an air-breathing engine.

[0054] The embodiments described herein can be combined with each other without exceeding the scope of protection of this invention.

[0055] The exhaust system 6 described above has many advantages.

[0056] First, the aforementioned exhaust system 6 allows for ideal noise reduction at low engine speeds, while simultaneously minimizing exhaust back pressure at high engine speeds.

[0057] In particular, by appropriately adjusting the width of each outlet orifice 10 (i.e., by appropriately adjusting the sound amplification / attenuation capability of each variable geometry end portion 9), the exhaust system 6 described above allows for optimization of the frequency response of each variable geometry end portion 9 under any possible operating conditions.

[0058] Furthermore, the aforementioned exhaust system 6 is particularly light and compact (especially in...) Figure 3 and Figure 4 The embodiment shown does not include the silencing device 14.

[0059] Finally, since it requires the addition of a few small, easily manufactured components compared to similar conventional exhaust systems 6, the aforementioned exhaust system 6 is easy to manufacture and inexpensive to produce.

[0060] List of reference numerals

[0061] 1. Car

[0062] 2. Front wheels

[0063] 3 Rear wheels

[0064] 4. Internal Combustion Heat Engine

[0065] 5 carriages

[0066] 6. Exhaust System

[0067] 7. Exhaust pipe

[0068] 8. Processing Unit

[0069] 9. End portion

[0070] 10 Outlet Holes

[0071] 11. Exhaust pipe

[0072] 12 Joints

[0073] 13. Outlet hole

[0074] 14. Silencing device

[0075] 15. Control valve

[0076] 16 Movable walls

[0077] 17. Actuator device

[0078] 18. Rotation axis

[0079] 19 Fixed Wall

[0080] 20 Control Units

Claims

1. An exhaust system (6) for an internal combustion engine (4); The exhaust system (6) includes at least one first exhaust pipe (7) originating from the internal combustion engine (4) and having an end portion (9) terminating at a first outlet port (10) through which exhaust gases are released into the atmosphere; The end portion (9) of the first exhaust pipe (7) has at least one movable wall (16) that can be moved to different positions to change the width of the outlet hole (10); and The exhaust system (6) is characterized in that: The end portion (9) of the first exhaust pipe (7) has two movable walls (16) opposite to each other. A motor-driven actuator device (17) is provided, which can be electronically controlled and configured to effectively move the two movable walls (16) together in opposite directions, so as to move the two movable walls (16) separately or to move the two movable walls (16) closer to each other; and A control unit (20) is provided, which is configured to change the position of the movable wall (16) by controlling the actuator device (17) according to the rotational speed of the internal combustion engine (4) and the engine load of the internal combustion engine (4).

2. The exhaust system (6) according to claim 1, characterized in that, The movable wall (16) is movable toward the maximum expansion position, in which the movable wall (16) gives the end portion (9) of the first exhaust pipe (7) a diverging structure that causes the area of ​​the cross section near the first outlet hole (10) to gradually increase.

3. The exhaust system (6) according to claim 1, characterized in that: The movable wall (16) can move between the maximum expansion position and the minimum expansion position; and At the maximum expansion position, the movable wall (16) gives the end portion (9) of the first exhaust pipe (7) a diverging structure that gradually increases the area of ​​the cross section near the first outlet hole (10).

4. The exhaust system (6) according to claim 3, characterized in that, At the position of minimum expansion, the movable wall (16) gives the end portion (9) of the first exhaust pipe (7) a parallel configuration that keeps the area of ​​the cross section near the first outlet hole (10) constant.

5. The exhaust system (6) according to claim 3, characterized in that, At the position of minimum expansion, the movable wall (16) gives the end portion (9) of the first exhaust pipe (7) a converging structure that gradually reduces the area of ​​the cross section near the first outlet hole (10).

6. The exhaust system (6) according to claim 1, characterized in that: The two movable walls (16) are hinged to rotate about two corresponding axes of rotation (18) that are parallel to each other; The end portion (9) of the first exhaust pipe (7) has two fixed walls (19) parallel to each other, the two fixed walls being perpendicular to the axis of rotation (18); and The two movable walls (16) are surrounded between the fixed wall (19) and move slowly on the fixed wall (19) when the two movable walls (16) move.

7. The exhaust system (6) according to claim 1, characterized in that, The exhaust system includes: A second exhaust pipe (11) originates from the joint (12) of the first exhaust pipe (7) and has a second outlet (13) through which exhaust gas is released into the atmosphere; and A silencer (14) is arranged along the second exhaust pipe (11).

8. The exhaust system (6) according to claim 7, characterized in that, The exhaust system includes a regulating valve (15) arranged downstream of the junction (12) from which the second exhaust pipe (11) originates, along the first exhaust pipe (7), and adapted to regulate the exhaust flow toward the end portion (9) of the first exhaust pipe (7).

9. The exhaust system (6) according to claim 7, characterized in that, Apart from the movable wall (16), the first exhaust pipe (7) has no silencing device arranged upstream of the movable wall (16), so the silencing device (14) is arranged only along the second exhaust pipe (11).

10. The exhaust system (6) according to claim 1, characterized in that: A regulating valve (15) is provided, which intersects with the first exhaust pipe (7) and is movable between a fully open position and a fully closed position; and In the fully closed position, the regulating valve (15) has a free section for the passage of exhaust gas, the area of ​​which is non-zero, such that exhaust gas can pass through the regulating valve (15) even when the valve (15) is in the fully closed position.

11. The exhaust system (6) according to claim 1, characterized in that, The control unit (20) is configured to move the movable wall (16) toward the minimum expansion position by controlling the actuator device (17) at low speed and low engine load of the internal combustion engine (4), and to move the movable wall (16) toward the maximum expansion position at high speed and high engine load of the internal combustion engine (4).

12. The exhaust system (6) according to claim 1, characterized in that, The control unit (20) is configured to also change the position of the movable wall (16) by controlling the actuator device (17) based on the gear engaged in the gearbox connected to the internal combustion engine (4), the longitudinal speed of the vehicle (1) equipped with the internal combustion engine (4), and the longitudinal acceleration of the vehicle (1) equipped with the internal combustion engine (4).

13. The exhaust system (6) according to claim 12, characterized in that, The control unit (20) is configured to move the movable wall (16) toward the minimum expansion position by controlling the actuator device (17) at a low position, and to move the movable wall (16) toward the maximum expansion position at a high position.

14. The exhaust system (6) according to claim 1, characterized in that, The control unit (20) is configured to detect: the rotational speed of the internal combustion engine (4), the engine load of the internal combustion engine (4), the gear engaged in the gearbox connected to the internal combustion engine (4), the longitudinal speed of the vehicle (1) equipped with the internal combustion engine (4), and / or the longitudinal acceleration of the vehicle (1) equipped with the internal combustion engine (4).

15. A vehicle (1), comprising: At least two drive wheels (3); An internal combustion engine (4) that rotates the two drive wheels (3) under the intervention of a gearbox, and is provided with an exhaust system (6) according to any one of claims 1 to 14.

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